1. Field of the Invention
The present invention relates to an electronic endoscope system constituted of an electronic endoscope and a processor between which signals are transmitted and received via radio waves.
2. Description of the Related Arts
Conventionally, medical diagnoses using electronic endoscopes are widely performed. In the electronic endoscope, an imaging sensor such as a CCD is incorporated in a front end portion of an insertion section for being inserted into a body cavity. Image signals obtained by the CCD are subject to signal processing in a processor to display an image of the body cavity, that is, an endoscopic image, on a monitor.
The conventional electronic endoscope and the processor are connected through a signal cable. However, a wireless electronic endoscope system is devised which transmits and receives the signals via radio waves without using the signal cable to improve operability of the electronic endoscope (see U.S. Pat. No. 4,633,304 and Japanese Patent Laid-Open Publication No. 2001-046334). In each reference, a modulating section for modulating the signals and a transmitter for transmitting the signals via the radio waves are provided in the electronic endoscope, and a receiver for receiving the radio Waves and a demodulating section for demodulating the radio waves into the original signals are provided in the processor.
The conventional electronic endoscope with the signal cable requires approximately 4 kV of dielectric strength voltage between a patient circuit in the electronic endoscope and a secondary circuit in the processor. However, such high dielectric strength voltage is unnecessary in the wireless electronic endoscope system since the signal cable is not used between the electronic endoscope and the processor.
In the wireless electronic endoscope system, since the processor receives image signals obtained by the electronic endoscope to display the endoscopic image on the monitor, synchronization between the electronic endoscope and the processor is needed.
However, in the conventional electronic endoscope systems, there is a need to use two channels of frequency bands, because the image signals and the synchronizing signals are transmitted in separate frequency bands.